Highly compressible open cord

Abstract

A cord (50) comprises a single layer (52) of helically wound metal filamentary elements (54). The metal filamentary elements define an internal enclosure (58) of the cord of diameter Dv. Each metal filamentary element (54) has a diameter Df and a helix radius of curvature Rf. With Dv, Df and Rf being expressed in millimetres, the cord satisfies the following relationships: 9≤Rf/Df≤30 and 1.30≤Dv/Df≤2.10.

The invention claimed is: 
     
       1. A cord comprising a single layer of helically wound metal filamentary elements,
 each metal filamentary element of the single layer describing, when the cord extends in a substantially rectilinear direction, a helical path about a main axis substantially parallel to the substantially rectilinear direction, such that, in a section plane substantially perpendicular to the main axis, a distance between the center of each metal filamentary element of the single layer and the main axis is equal to half a helix diameter Dh and is substantially constant and identical for all the metal filamentary elements of the single layer, 
 the metal filamentary elements defining an internal enclosure of a cord of diameter Dv, and 
 each metal filamentary element having a diameter Df and a helix radius of curvature Rf defined by Rf=P/(π×Sin(2α)), where P is a pitch of each metal filamentary element expressed in millimeters and a is a helix angle of each metal filamentary element, 
 wherein, with Dh, Dv, Df and Rf being expressed in millimeters 9≤Rf/Df≤30 and 1.30≤Dv/Df≤2.10, where Dv=Dh−Df. 
 
     
     
       2. The cord according to  claim 1 , wherein 11≤Rf/Df≤19. 
     
     
       3. The cord according to  claim 1 , wherein 1.30≤Dv/Df≤2.05. 
     
     
       4. The cord according to  claim 1 , wherein the helix radius of curvature Rf is such that 2 mm≤Rf≤7 mm. 
     
     
       5. The cord according to  claim 1 , wherein the helix diameter Dh of each metal filamentary element is such that 0.40 mm≤Dh≤1.50 mm. 
     
     
       6. The cord according to  claim 1 , wherein 0.10 mm≤Df≤0.50 mm. 
     
     
       7. The cord according to  claim 1 , wherein Dv≥0.46 mm. 
     
     
       8. The cord according to  claim 1 , wherein each metal filamentary element is wound at a pitch P such that 3 mm≤P≤15 mm. 
     
     
       9. The cord according to  claim 1 , wherein the cord has a diameter D such that D≤2.00 mm. 
     
     
       10. The cord according to  claim 1 , wherein a ratio K of the pitch P to the diameter Df of each metal filamentary element, P and Df being expressed in millimeters, is such that 19≤K≤44. 
     
     
       11. The cord according to  claim 1 , wherein the helix angle α of each metal filamentary element is such that 13°≤α≤21°. 
     
     
       12. The cord according to  claim 1 , wherein the cord has a structural elongation As such that As≥1%, the structural elongation As being determined by applying the standard ASTM D2969-04 of 2014 to the cord so as to obtain a force-elongation curve, and the structural elongation As being equal to elongation, in %, corresponding to a maximum gradient of a force-elongation curve. 
     
     
       13. A semifinished product comprising an elastomeric matrix in which the cord according to  claim 1  is embedded. 
     
     
       14. A tire comprising a filamentary reinforcing element obtained by embedding the cord according to  claim 1  in an elastomeric matrix. 
     
     
       15. The tire according to  claim 14 , wherein the tire comprises a crown comprising a tread and a crown reinforcement, two sidewalls, two beads, and a carcass reinforcement that is anchored in each of the beads and extends in the sidewalls and in the crown, each sidewall connecting each bead to the crown, the crown reinforcement extending in the crown in a circumferential direction of the tire, the crown reinforcement being radially interposed between the carcass reinforcement and the tread, and the crown reinforcement comprising the filamentary reinforcing element.